1. Field of the Invention
The present invention relates to an optical image stabilizer for a camera module capable of moving in first and second directions around a camera module using polymer elements.
2. Description of the Related Art
In general, as a large amount of still cameras and digital video cameras are widely provided, consumers increasingly want to take pictures and videos in high quality. In particular, a Complementary Metal Oxide Semiconductor (CMOS) sensor is preferred over a Charge Coupled Device (CCD) sensor as an image sensor for digital cameras. The reason is that the CCD sensor has better characteristics in image quality than the CMOS sensor, but the CMOS sensor has been increasing its market share because the CCD sensor has drawbacks of high power consumption and complicated construction thereof. Recently, however, the CMOS sensor's image quality has been improved. As image sensors such as CCD and CMOS sensors have been developed, digital cameras have become popular and widely used, and further a camera module using such image sensors is applied to a portable terminal like a cellular phone.
In the case of using a CMOS sensor, the definition of an object image is remarkably decreased due to the user shaking the camera. This shaking of the camera is commonly caused by the shaking of the hand of the user. Recently, an optical image stabilizer has been increasingly employed in order to prevent the decrease of the image definition due to external vibrations or the shaking the camera.
A typical optical image stabilizer for a camera module has two types of compensation devices: one type is designed to move an image sensor, and the other is to move a lens.
The compensation device for moving the image sensor includes a moving device which detects the movement of a mechanism by means of a plurality of angular velocity sensors and then moves the image sensor in accordance with a detected angular velocity and direction thereof, thereby compensating the object image captured on the surface of the image sensor.
In contrast, the compensation device for moving the lens includes a plurality of lenses. This device arbitrarily deflects the incident ray of light using a lens or prism which can be variably moved or deflected, or controls the input position of the image sensor, thereby removing any unstable images to provide a clear image.
However, conventional optical image stabilizers described hereinabove are disadvantageous in that the camera module includes a separate moving device near the image sensor or consists of a plurality of lenses, which causes the camera module to become large. Hence, it is difficult for conventional image stabilizers to be applied in an extremely small and complicated lens system. In addition, the camera module cannot be installed in a product such as a portable terminal which has difficulties in providing a mounting space for components therein. In order for making the optical image stabilizer of a small size to resolve the above drawbacks, the lens should be much smaller accordingly, which results in difficulties in obtaining clear images.
Further, conventional optical image stabilizers have drawbacks as it is difficult to assure their reliability against impacts due to being dropped or jarred. Therefore, an optical image stabilizer which can be applied to an extremely small and complicated lens system of a camera module is required.